to allot proportions of the combined egg count to 

 the various size intervals. All eggs were counted in 

 the remaining 45 subsamples to provide with the 

 previous 5 subsamples, 50 counts of eggs per unit 

 volume The total number of eggs in the ovary was 

 calculated from the product of mean subsample 

 count per milliliter and the reservoir volume prior 

 to subsampling. The number of eggs in various size 

 categories was obtained by applying the appropri- 

 ate proportional value to the estimated total number 

 of eggs in the ovary. Subsample egg counts averaged 

 between 50 and 150 eggs, with the majority falling 

 within 75 and 100. Size-frequency histograms were 

 based on 250-750 sized eggs with the majority bas- 

 ed on 375-500 sized eggs. Initial procedural evalua- 

 tion indicated that 200 sized eggs was sufficient to 

 obtain a replicable size-frequency distribution. 



Eighteen ovaries from postspawned females 

 were collected on 3 July 1981 and were similarly 

 processed. 



Prespawning females collected in 1981 were ag- 

 ed by the otolith break and burn method (Chilton and 

 Beamish 1982). 



Results and Discussion 



Frequency Distributions of 

 Oocyte Diameter for Prespawners 



Most of the 97 ovaries of prespawners examined 

 contained a pronounced bimodal distribution of 

 oocyte diameters with peaks at about 100 p*m and 

 between 500 and 600 ^m (Figs. 1-3). Oocytes <150 

 jjm in diameter contained no yolk materials and are 

 taken to constitute a reserve fund for subsequent 

 years (Foucher and Beamish 1980). Oocytes >150 ^m 

 diameter were undergoing vitellogenesis, and a few 

 ovaries contained nonhydrated oocytes reaching 

 700-750 nm diameter. Hydrated eggs were not seen 

 in these ovaries collected in early March and hydra- 

 tion probably does not occur in oocytes <700 /urn, 

 although hydrated oocytes from 350 to 950 /^m 

 diameter were found by Foucher and Beamish 

 (1980). This apparent discrepancy may reflect their 

 underestimation of oocyte diameters in histological 

 preparations of translucent oocytes due to the plane 

 of sectioning. 



The unimodal distribution of yolked oocytes, also 

 reported for M. m. hubbsi in the Argentine Sea 

 (Christiansen and Cousseau 1971) does not comple- 

 ment the findings of MacGregor (1966, 1971). He 

 found that ovaries of prespawning coastal hake taken 

 off Baja California contained distinct groups of 

 "small" and "large" yolked oocytes, of which only the 



latter were destined for release Furthermore, Er- 

 makov et al. (1974) reported 21% of the 93 female 

 Pacific hake taken off Baja California in 1972 had 

 unimodal, 55% bimodal, 18% trimodal, and 6% 

 quadrimodal oocyte distributions. Similarly, their 

 subsequent sample of 45 ovaries collected in the 

 Oregon-Washington region in late November contain- 

 ed 22% unimodal, 65% bimodal, and 6% trimodal 

 distributions, with major peaks at 200 and 600 /um 

 diameter. Nearly half of the ovaries collected and ex- 

 amined by Ermakov et al. (1974) did not contain a 

 bimodal distribution of yolked oocytes, although 

 these authors concluded that asynchronous develop- 

 ment of yolked oocytes indicated the probability of 

 multiple spawnings, most likely two batches within 

 the spawning season. 



Estimates of Total Fecundity 



Standard errors of mean egg counts for total 

 fecundity estimates of total fecundity (oocytes ^40 

 (jm diameter) ranged between 0.4 and 4.4% of the 

 means and were <3% in nearly 70% of the 97 ovaries 

 processed. The variability of the enumeration tech- 

 nique compares favorably with that reported by 

 Mason et al. (1983) in an analysis of the fecundity 

 of the sablefish, Anoplopoma fimbria, and with that 

 reported by Pitt (1963) on the fecundity of the 

 American plaice Hippoglossoides platessoides, using 

 Wiborg's whorling vessel (Wiborg 1951). 



The estimates of total fecundity (oocytes ^40 ^m 

 diameter) increased with fork length according to 

 the equation F = 0.3081FL 3 - 7605 , [where FL = fork 

 length in centimeters]. The correlation coefficient 

 (r) for the regression was 0.93. An insignificant F 

 ratio from analysis of variance of slope and inter- 

 cept values allowed pooling of the 1980 and 1981 

 data. 



The smallest and largest Pacific hake females in 

 the sample (39 and 82 cm FL) contained estimated 

 total oocyte complements of 202,100 and 3,009,900 

 oocytes >40 ^m, respectively. All 97 fecundity esti- 

 mates fell within the range of 165,700 and 3,108,000 

 oocytes ^40 \xm. 



Estimates of Fecundity Within 

 Size Classes of Oocytes 



The estimated number of oocytes with 20 \xm in- 

 tervals of diameter were summed within five inter- 

 vals and regressed against fork length to examine 

 the correlation coefficients (Table 1). Coefficients 

 declined progressively with increased oocyte 

 diameter, reflecting increasing variability among 



210 



